How Cats Drink: Inertia, Gravity, and the Froude Number at the Tip of a Tongue
Cats do not scoop water with their tongues — they exploit a delicate balance between inertia and gravity at the air-water interface. The tip of the tongue just touches the surface; rapid withdrawal pulls a fluid column upward; the jaw closes at exactly the moment the column peaks. Reis, Jung, Aristoff, and Stocker (Science, 2010) showed that the lapping frequency of all felids — from domestic cats to lions — is tuned so that the Froude number at the tongue tip is approximately unity.